This invention relates to a method and apparatus for connecting a rear trailer in a tractor-trailer assembly, and more particularly to a method and apparatus for positioning a mobile connector carrier between a front and rear trailer for connection to both trailers.
In the trucking industry, more and more states are permitting the hauling of freight over the road in more than one trailer, connected in tandem with a tractor. The connection of a single trailer to a tractor is relatively simple since the tractor carrying a sloping fifth wheel connector on the rear of its chassis is backed beneath the front end of the stationary trailer until the connector or king pin on the front end of the trailer is properly seated and locked within the slot of the fifth wheel connector. However, the connection of a second trailer to the rear of the first trailer is more involved and takes substantially more time than the connection of one trailer to a tractor. The connection of a second trailer usually requires approximately 45-50 minutes.
In order to assemble two or more trailers in tandem to a tractor, the tractor is first connected to the front end of a front trailer in a conventional manner, that is by backing the tractor beneath the front end of the trailer. However, since conventional trailers are not equipped with fifth wheel connectors, a separate mobile carrier, or dolly, supporting a connector member, and specifically a fifth wheel connector, must be located and connected by its tongue to the cooperating connector on the rear end of the front trailer. This tandem assembly, including the tractor, the trailer, and the mobile connector carrier, one of which is known in the trade as a "JIFFLOX", is driven to a position as close as possible to the front end of a second or rear trailer. Since the assembly cannot be moved rearwardly more than approximately twelve feet without the connector carrier jack-knifing, the operator of the tractor must first manually unhook the carrier from the rear end of the front trailer and push it by hand to a position as close as possible to the front end of the rear trailer. Then the operator returns to his tractor and backs the front trailer slowly and carefully toward the carrier, attempting to stop approximately one foot before the rear end of the front trailer engages the tongue of the carrier. This part of the operation is extremely tedious since the driver or operator must use extreme caution in lining up the front trailer and the carrier with the rear trailer so that after the carrier is re-connected to the front trailer, the carrier does not jack-knife as the front trailer is moved rearwardly to the front end of the rear trailer. Moreover, care must be taken not to strike the tongue of the carrier against the rear end of the front trailer, which is invisible to the operator as the tractor and front trailer move rearwardly.
After the front trailer is moved as close as possible to the carrier, the operator again gets out of the tractor, goes to the rear of the front trailer and manually re-connects the carrier to the rear of the front trailer. The operator again returns to the tractor and backs up the front trailer and mobile connector carrier until the connector or king pin on the front end of the rear trailer is locked in the fifth wheel slot of the carrier by the automatic catch mechanism. All of the vehicles which are elements of the tandem assembly are now connected. The landing gear on the rear trailer is elevated and the air and electric lines are connected to ender the entire tandem assembly road-ready.
The mobile connector carrier, one of which is known as the "JIFFLOX", is relatively heavy, in the order of 3,000 pounds, and requires considerable strength in order to merely pull the carrier forward in order to connect the tongue to the rear end of a front trailer. Occasionally, an operator who pulls the carrier incurs an injury to is back or to his hands.
One attempt to solve the problems in connecting trailers in a tandem trailer assembly is presented in prior U.S. Pat. No. 4,653,771, of Gieg, issued Mar. 31, 1987. In the Gieg system, a laterally shiftable platform must be utilized in order to laterally shift a rear trailer into a position behind a tandem assembly including the tractor, front trailer, and the already manually connected mobile connector carrier or dolly After the rear trailer is shifted into longitudinal alignment behind the tandem assembly, the tandem assembly is moved rearwardly to automatically connect the carrier with the front end of the rear trailer.
The following U.S. patents disclose various types of lift attachments for forklift trucks including a load engaging mechanism rotatable with respect to a boom projecting from the forklift:
U.S. Pat. No. 2,699,878, Bertram Jan. 18, 1955 PA1 U.S. Pat. No. 4,474,495, Ledwell, Jr. Oct. 2, 1984 PA1 U.S. Pat. No. 4,664,576, Coe May 12, 1987
The Bertram and the Ledwell, Jr. patents disclose load engaging mechanisms which are rotatable about a vertical axis, and provided with a rotary drive mechanism for rotating the load relative to the boom. However, the load engaging mechanism of the Bertram patent is specifically designed for gripping or supporting beneath the opposite side edges of such loads as sheet material, including plaster board, insulation board, plywood, sheet metal, or other sheet material.
The load clamping mechanism of the Ledwell, Jr. U.S. Pat. No. 4,474,495 is designed to engage chicken coops.
The Coe U.S. Pat. No. 4,664,576 is provided with opposed clamping jaws both of which are designed, not only to move toward and away from each other, but jointly about a horizontal axis in order to grip and turn completely over an elongated cargo containing trailer chassis about its longitudinal axis.
None of the above patents disclose any mechanism which could be adapted to, or which would be suitable for engaging a mobile connector tractor, known in the trade as a "JIFFLOX", which could lift the JIFFLOX, rotate it when desired, and position it within the narrow confines of the working space between a front and rear trailer in a tandem tractor-trailer assemble.